A premixing and stable combustion method and device for a tank furnace

Abstract

The application discloses a kind of premixing combustion stabilization method and device of tank furnace, belongs to calcined coke production technical field, using preheated air and cold air mix, participate in volatile combustion, make first layer fireway negative pressure-50~‑20Pa;The eighth layer fireway negative pressure is-180~‑120Pa;Gate negative pressure is-250~‑150Pa;First layer fireway temperature is 1260~1320 ℃;Second layer fireway temperature is 1260~1320 ℃;The eighth layer fireway temperature is 1060~1120 ℃;Exhaust fume temperature is 1040~1100 ℃.The application is by using the method of preheated air and cold air mixing combustion-supporting, maintains the stability of flame distribution in fireway.

Description

Technical Field

[0001] This invention belongs to the field of calcined coke production technology, and particularly relates to a premixed combustion stabilization method and apparatus for a pot furnace. Background Technology

[0002] With the rapid development of the non-ferrous metals industry and the new energy industry, the demand for petroleum coke, as a basic raw material, is huge. In 2021, the national output of calcined coke exceeded 30 million tons. Compared with rotary kilns, pot furnaces have advantages such as lower carbon loss and better product quality in the production of calcined coke. Traditional pot furnaces utilize preheated air from the cooling bottom channel to participate in the combustion of volatiles. Faced with increasingly deteriorating raw materials, the volatile content has increased significantly, causing excessive heat input into the furnace body and high flue temperature, resulting in technical problems such as "over-calcination" of calcined coke, high carbon loss rate, and short furnace life. Therefore, the pot furnace process has begun to change to a cold air-assisted combustion process, which has the following advantages:

[0003] 1) Cold air is the same as room temperature air. It is the opposite of preheated air. It can significantly reduce the temperature inside the combustion chamber, by 100-150°C compared to the combustion chamber temperature in the preheated air combustion process. This can accommodate raw materials with high volatile content and will not cause the problem of "over-calcination" of the calcined coke.

[0004] 2) All volatile components enter the fire duct from the first floor of the front wall. Because cold air supports combustion, the combustion temperature will not be too high, and it will not easily burn the refractory material in the flame zone. All the combustion air is located in one place, and the fire duct temperature is controlled by adjusting the cold air damper. The operation is simple, and new employees can be put into operation after a period of simple training without extensive experience.

[0005] However, after a period of production, the drawbacks of the cold air combustion process have become apparent. The main issue is that during the adjustment of the cold air valves, when the volatile content increases, the valve opening is widened to maintain the fire channel temperature. When the valve opening reaches a certain level, a "flame suspension" phenomenon occurs, causing temperature stratification in the first-layer fire channel. The upper space is dominated by high-temperature flames, while the lower space is dominated by cold air. Furthermore, the flames are stretched out and penetrate the second layer, impacting the thermocouples. Simultaneously, the material temperature in the corresponding storage tank area is low, and the volatile matter escape rate from the raw coke is lower than normal. The volatile matter cannot escape in time in the upper area of ​​the storage tank and is carried to the lower area by the powder, easily causing deflagration at the crusher. In severe cases, this can damage the crusher equipment, leading to storage tank shutdown and maintenance.

[0006] Therefore, it is necessary to develop a stable combustion process that can satisfy both simple and convenient temperature control operation and achieve premixed stable combustion effect. Summary of the Invention

[0007] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a premixed combustion stabilization method and apparatus for a can furnace. By using a method of mixing preheated air and cold air to assist combustion, the stability of the flame distribution in the fire channel is maintained. This avoids the overheating phenomenon that occurs when all preheated air is used for combustion, as well as the situation where the flame is suspended and the combustion is unstable when only cold air is used for combustion, making the can furnace production process more stable.

[0008] To achieve the above objectives, the main technical solutions adopted by the present invention include:

[0009] A premixed combustion stabilization method for a canister furnace involves mixing preheated air and cold air, which then participates in the combustion of volatiles. This results in a negative pressure of -50 to -20 Pa in the first-layer fire channel; -180 to -120 Pa in the eighth-layer fire channel; -250 to -150 Pa at the gate; a temperature of 1260 to 1320 °C in the first-layer fire channel; a temperature of 1260 to 1320 °C in the second-layer fire channel; a temperature of 1060 to 1120 °C in the eighth-layer fire channel; and a flue gas temperature of 1040 to 1100 °C.

[0010] Furthermore, the temperature of the preheated air and cold air after mixing is 300~400℃ in the air premixing channel, and the premixed air is drawn in through the negative pressure of the first-floor fire channel.

[0011] Furthermore, the preheated air is ambient temperature air that has passed through the cooling furnace bottom below the furnace flue of the tank furnace and exchanged heat with the high-temperature calcined coke, and then enters the air premixing channel through the preheated air vertical channel, and is drawn in through the negative pressure of the first layer flue.

[0012] Furthermore, the flow rate of preheated air entering the air premixing channel is adjusted by a preheated air pull plate set at the preheated air channel.

[0013] Furthermore, the cold air flow rate is adjusted by a manual pull plate or an automatic damper set at the inlet, and the cold air is automatically drawn into the air premixing channel through the negative pressure of the fire duct.

[0014] The premixed stable combustion pot furnace device implementing the method includes fire channels distributed from top to bottom. A furnace bottom cooling horizontal channel is provided at the bottom of the fire channels. The inlet of the furnace bottom cooling horizontal channel is located below the bottom fire channel on the rear wall. The outlet of the furnace bottom cooling horizontal channel is connected to a preheated air collection channel. The preheated air collection channel is connected to a preheated air vertical channel to deliver preheated air to the corresponding position on the upper part of the fire channels. A preheated air flow regulating device is provided at the outlet of the preheated air vertical channel. An air premixing channel is provided above the outlet of the preheated air vertical channel. A cold air channel is provided on one side of the air premixing channel. The inlet of the cold air channel is located directly below the inlet of the first layer fire channel on the front wall. A cold air flow regulating device is provided at the inlet of the cold air channel. A volatile matter vertical channel is provided from top to bottom on the top of the pot furnace. The outlet of the volatile matter vertical channel is connected to the outlet of the air premixing channel and the first layer fire channel.

[0015] The beneficial effects of this invention are: the premixed stable combustion method of this invention can leverage the advantages of using preheated air and cold air to aid combustion, maintaining combustion stability, solving the problem of flame suspension, and enabling simple and quick temperature adjustment. It improves the adaptability of the furnace to the volatile content of raw materials, broadens the fluctuation range of volatiles in the raw materials, and reduces enterprise production costs. Attached Figure Description

[0016] Figure 1 This is a longitudinal cross-sectional view of the internal fire channel of the premixed stable combustion tank furnace of the present invention.

[0017] In the diagram: 1. Horizontal cooling channel at the bottom of the furnace; 2. Preheating air collection channel; 3. Vertical preheating air channel; 4. Preheating air pull plate; 5. Cold air channel; 6. Air premixing channel; 7. Vertical volatile matter channel; 8. Fire channel. Detailed Implementation

[0018] To better explain and facilitate understanding of the present invention, a detailed description of the invention is provided below with reference to the accompanying drawings and specific embodiments. In this document, directional terms such as "upper," "lower," etc., are used interchangeably with other directional terms. Figure 1 The orientation is used as a reference.

[0019] This invention provides a premixed combustion stabilization method and apparatus for a tank furnace, used for premixed combustion stabilization of calcined coke, a basic raw material required by industries such as non-ferrous metals, new energy battery anode materials, and special carbon materials.

[0020] The premixed combustion stabilization method for a canister furnace proposed in this invention involves mixing preheated air and cold air to participate in the combustion of volatiles. The ratio of preheated air to cold air depends on the volatile content in the raw materials and the negative pressure in the combustion chamber. The preheated air is mainly used to improve combustion stability, and the preheated air baffle is fixed during normal production. The cold air is mainly used to regulate the temperature distribution in the combustion chamber, and the stable combustion chamber temperature is controlled by adjusting the cold air valve to control the amount of cold air entering the combustion chamber during normal production.

[0021] The negative pressure control of the fire channel is as follows:

[0022] The negative pressure in the first-floor fire duct (measured at the observation hole on the rear wall) is -50 to -20 Pa; the negative pressure in the eighth-floor fire duct (measured at the observation hole on the rear wall) is -180 to -120 Pa; and the negative pressure at the gate is -250 to -150 Pa. This negative pressure setting, in conjunction with the regulating valve, facilitates the control of the automatic intake of premixed air and promotes the formation of a saturated flame, stable combustion, and reduces the likelihood of diffused flames and flame suspension.

[0023] The temperature control of the fire channel is as follows:

[0024] First layer (1.5m thermocouple measuring point on the rear wall): 1260~1320℃; Second layer (1.5m thermocouple measuring point on the rear wall): 1260~1320℃; Eighth layer: 1060~1120℃; Exhaust gas temperature: 1040~1100℃. This temperature setting is beneficial for the stability of the combustion flame and makes the production process more stable, with minimal impact of adjusting the amount of cold air on the flame shape.

[0025] The preheated air and cold air are mixed and the temperature in the air premixing channel is 300~400℃, which can increase the combustion rate of volatiles and combustion air, making the combustion more complete, and is drawn in through the negative pressure of the first-floor fire channel.

[0026] The preheating air is ambient temperature air that has undergone heat exchange with the high-temperature calcined coke after passing through the cooling furnace bottom below the furnace flue. It then enters the air premixing channel through the preheating air vertical duct and is drawn in under negative pressure from the first-layer flue. The flow rate of the preheating air entering the air premixing channel is adjusted by a preheating air baffle plate located at the preheating air channel.

[0027] The flow rate of cold air is adjusted by a manual pull plate or an automatic damper set at the inlet, and the cold air is automatically drawn into the air premixing channel through the negative pressure of the first-floor fire duct.

[0028] This invention employs a method of mixing preheated and cold air for combustion, maintaining the stability of the flame distribution within the combustion chamber. This avoids both the overheating issues that occur with all-preheated air combustion and the unstable flame and combustion problems that arise with single-air combustion, resulting in a more stable production process for the tank furnace. It also enables simple and quick temperature adjustment. Furthermore, it improves the adaptability of the tank furnace to the volatile content of raw materials, broadens the range of volatile content fluctuations in the raw materials, and reduces production costs for enterprises.

[0029] The present invention also provides a premixed, stable-fired furnace apparatus for implementing the method, such as... Figure 1As shown, the furnace includes fire channels 8 distributed from top to bottom. A bottom cooling horizontal channel 1 is located at the bottom of the fire channel 8. The inlet of the bottom cooling horizontal channel 1 is located below the bottom fire channel on the rear wall. The outlet of the bottom cooling horizontal channel 1 is connected to a preheating air collection channel 2, which is connected to a preheating air vertical channel 3, delivering preheated air to the corresponding position at the top of the fire channel 8. A preheating air flow regulating device, specifically a preheating air pull plate 4, is located at the outlet of the preheating air vertical channel 3 to regulate the preheating air flow. An air premixing channel 6 is connected above the outlet of the preheating air vertical channel 3. A cold air channel 5 is located on one side of the air premixing channel 6. The inlet of the cold air channel 5 is located directly below the inlet of the first-layer fire channel on the front wall. The changes in the first-layer flame can be observed while operating the valve. A cold air flow regulating device, specifically a manual pull plate or an automatic damper, is located at the inlet of the cold air channel 5 to regulate the cold air flow. The top of the furnace is equipped with a volatile matter vertical channel 7 from top to bottom. The outlet of the volatile matter vertical channel 7 is connected to the outlet of the air premixing channel 6 and the first-floor fire channel.

[0030] Air exchanges heat with the high-temperature calcined coke in the horizontal cooling channel 1 below the furnace bottom of the furnace fire channel 8. After being collected by the same group of preheated air, it enters the preheated air collection channel 2, and then enters the preheated air vertical channel 3. The flow rate is regulated by the preheated air pull plate 4, and then enters the air premixing channel 6. Cold air (i.e., ambient temperature air) has its flow rate regulated by a manual pull plate or an automatic damper, and enters the air premixing channel 6 through the cold air channel 5. The cold air inlet is located directly below the inlet of the first-level fire channel on the front wall. After the cold air and preheated air are mixed, they enter the air premixing channel 7, and then mix with the volatiles coming down from the volatiles vertical channel 8 for combustion. The mixture is then drawn into the first-level fire channel by the negative pressure.

[0031] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any modifications, alterations, substitutions, and variations made by those skilled in the art to the above embodiments are within the scope of the present invention.

Claims

1. A premixed combustion stabilization method for a pot furnace, characterized in that: The mixture of preheated and cold air participates in the combustion of volatiles, resulting in a negative pressure of -50 to -20 Pa in the first-layer fire duct; -180 to -120 Pa in the eighth-layer fire duct; and -250 to -150 Pa at the gate. The temperature of the first-layer fire duct is 1260 to 1320℃; the temperature of the second-layer fire duct is 1260 to 1320℃; the temperature of the eighth-layer fire duct is 1060 to 1120℃; and the exhaust temperature is 1040 to 1100℃. The temperature of the preheated and cold air mixture at the air premixing channel is 300 to 400℃, and the premixed air is drawn in through the negative pressure of the first-layer fire duct. The preheating air is ambient temperature air that has undergone heat exchange with the high-temperature calcined coke in the furnace bottom cooling horizontal channel below the furnace fire channel, enters the air premixing channel through the preheating air vertical channel, and is drawn in through the negative pressure of the first layer fire channel.

2. The premixed combustion stabilization method for a pot furnace according to claim 1, characterized in that: The flow rate of preheated air entering the air premixing channel is adjusted by a preheated air pull plate set at the preheated air channel.

3. The premixed combustion stabilization method for a pot furnace according to claim 1, characterized in that: The flow rate of cold air is adjusted by a manual pull plate or an automatic damper set at the inlet, and the cold air is automatically drawn into the air premixing channel through the negative pressure of the fire duct.

4. A premixed, stable-combustion furnace apparatus for implementing the method of any one of claims 1-3, comprising fire channels distributed from top to bottom, characterized in that, A horizontal cooling channel is provided at the bottom of the fire channel. The inlet of the horizontal cooling channel is located at the lower part of the bottom fire channel on the rear wall. The outlet of the horizontal cooling channel is connected to the preheating air collection channel. The preheating air collection channel is connected to the preheating air vertical channel, which delivers the preheating air to the corresponding position at the top of the fire channel. The outlet of the preheating air vertical channel is equipped with a preheating air flow regulating device. An air premixing channel is provided above the outlet of the preheating air vertical channel. A cold air channel is provided on one side of the air premixing channel. The inlet of the cold air channel is located directly below the inlet of the first-layer fire channel on the front wall. The inlet of the cold air channel is equipped with a cold air flow regulating device. A volatile matter vertical channel is provided from top to bottom on the top of the furnace. The outlet of the volatile matter vertical channel is connected to the outlet of the air premixing channel and the first-layer fire channel.

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